Microsorum? collected in New Guinea.

From the enquirer:

I am hoping you can help with identification of the attached fern. It is in a greenhouse at the University of Massachusetts, with a label indicating only that it was collected in New Guinea by a man named Bierhorst. The current greenhouse director says that Bierhorst was an earlier director of the greenhouse; she has no identification for the plant.

The first attached photo shows sori on the underside of a frond. The second (I hope) gives some sense for the growth pattern. The longest fronds are roughly six inches (15 cm) long.

I am aware that fern ID can be extremely difficult, and that New Guinea ranks among the most biologically diverse regions on the planet. I would be quite happy with identification to genus, if species is not possible. Do you think you can help with identification of this fern?

Advice appreciated, Thanks, Brian Swale           Email = Brian Swale